Documentation

RoughPaths.Word.Geometric

Weakly Geometric Rough Paths #

This file gives the named weakly geometric rough path layer. In the current library this is the algebraic, group-like signature-valued notion: increments satisfy Chen's identity and the shuffle identities. The metric closure definition of geometric rough paths can be added once the corresponding topology on truncated tensor algebras is available.

Main definitions #

@[reducible, inline]
abbrev RoughPaths.WeakGeometricRoughPath (T : Type u) (α : Type v) (R : Type w) [CommSemiring R] :
Type (max u v w)

A weakly geometric rough path is a Hopf rough path over the word shuffle Hopf algebra: increments are characters — group-like signature series — and Chen's identity is convolution in the character monoid.

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    The underlying group-like algebraic rough path.

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      Regard an algebraic group-like rough path as weakly geometric.

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        theorem RoughPaths.WeakGeometricRoughPath.ext {T : Type u} {α : Type v} {R : Type w} [CommSemiring R] {X Y : WeakGeometricRoughPath T α R} (h : X.toAlgebraic = Y.toAlgebraic) :
        X = Y

        Weakly geometric rough paths are equivalent to group-like algebraic ones.

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        • One or more equations did not get rendered due to their size.
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          The constant identity weakly geometric rough path.

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            def RoughPaths.WeakGeometricRoughPath.comapTime {T : Type u} {α : Type v} {R : Type w} [CommSemiring R] {S : Type z} (f : ST) (X : WeakGeometricRoughPath T α R) :

            Pull a weakly geometric rough path back along a map of time domains.

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              def RoughPaths.WeakGeometricRoughPath.comapMapLetters {T : Type u} {α : Type v} {R : Type w} [CommSemiring R] {β : Type z} (f : αβ) (X : WeakGeometricRoughPath T β R) :

              Pull a weakly geometric rough path back along a map of alphabets.

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                def RoughPaths.WeakGeometricRoughPath.increment {T : Type u} {α : Type v} {R : Type w} [CommSemiring R] (X : WeakGeometricRoughPath T α R) (s t : T) :
                List αR

                Signature increment of a weakly geometric rough path.

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                  def RoughPaths.WeakGeometricRoughPath.coeff {T : Type u} {α : Type v} {R : Type w} [CommSemiring R] (X : WeakGeometricRoughPath T α R) (s t : T) (word : List α) :
                  R

                  Coordinate of a weakly geometric rough path increment on a word.

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                    Truncated signature increment of a weakly geometric rough path.

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                      @[simp]
                      @[simp]
                      theorem RoughPaths.WeakGeometricRoughPath.coeff_apply {T : Type u} {α : Type v} {R : Type w} [CommSemiring R] (X : WeakGeometricRoughPath T α R) (s t : T) (word : List α) :
                      X.coeff s t word = X.toAlgebraic.coeff s t word
                      @[simp]
                      theorem RoughPaths.WeakGeometricRoughPath.truncatedIncrement_apply {T : Type u} {α : Type v} {R : Type w} [CommSemiring R] (X : WeakGeometricRoughPath T α R) (n : ) (s t : T) (word : { word : List α // word.length n }) :
                      X.truncatedIncrement n s t word = X.coeff s t word
                      @[simp]
                      theorem RoughPaths.WeakGeometricRoughPath.unit_increment {T : Type u} {α : Type v} {R : Type w} [CommSemiring R] (s t : T) :
                      (unit T α R).increment s t = Word.unit α R
                      @[simp]
                      theorem RoughPaths.WeakGeometricRoughPath.unit_coeff_nil {T : Type u} {α : Type v} {R : Type w} [CommSemiring R] (s t : T) :
                      (unit T α R).coeff s t [] = 1
                      @[simp]
                      theorem RoughPaths.WeakGeometricRoughPath.unit_coeff_cons {T : Type u} {α : Type v} {R : Type w} [CommSemiring R] (s t : T) (a : α) (word : List α) :
                      (unit T α R).coeff s t (a :: word) = 0
                      @[simp]
                      theorem RoughPaths.WeakGeometricRoughPath.coeff_comapTime {T : Type u} {α : Type v} {R : Type w} [CommSemiring R] {S : Type z} (f : ST) (X : WeakGeometricRoughPath T α R) (s t : S) (word : List α) :
                      (comapTime f X).coeff s t word = X.coeff (f s) (f t) word
                      @[simp]
                      theorem RoughPaths.WeakGeometricRoughPath.coeff_comapMapLetters {T : Type u} {α : Type v} {R : Type w} [CommSemiring R] {β : Type z} (f : αβ) (X : WeakGeometricRoughPath T β R) (s t : T) (word : List α) :
                      (comapMapLetters f X).coeff s t word = X.coeff s t (List.map f word)
                      @[simp]
                      theorem RoughPaths.WeakGeometricRoughPath.truncatedIncrement_comapTime {T : Type u} {α : Type v} {R : Type w} [CommSemiring R] {S : Type z} (f : ST) (X : WeakGeometricRoughPath T α R) (n : ) (s t : S) :
                      (comapTime f X).truncatedIncrement n s t = X.truncatedIncrement n (f s) (f t)
                      @[simp]
                      theorem RoughPaths.WeakGeometricRoughPath.truncatedIncrement_comapMapLetters {T : Type u} {α : Type v} {R : Type w} [CommSemiring R] {β : Type z} (f : αβ) (X : WeakGeometricRoughPath T β R) (n : ) (s t : T) :
                      (comapMapLetters f X).truncatedIncrement n s t = fun (word : { word : List α // word.length n }) => X.coeff s t (List.map f word)
                      @[simp]
                      theorem RoughPaths.WeakGeometricRoughPath.increment_self {T : Type u} {α : Type v} {R : Type w} [CommSemiring R] (X : WeakGeometricRoughPath T α R) (t : T) :
                      X.increment t t = Word.unit α R
                      @[simp]
                      theorem RoughPaths.WeakGeometricRoughPath.coeff_self_nil {T : Type u} {α : Type v} {R : Type w} [CommSemiring R] (X : WeakGeometricRoughPath T α R) (t : T) :
                      X.coeff t t [] = 1
                      @[simp]
                      theorem RoughPaths.WeakGeometricRoughPath.coeff_self_cons {T : Type u} {α : Type v} {R : Type w} [CommSemiring R] (X : WeakGeometricRoughPath T α R) (t : T) (a : α) (word : List α) :
                      X.coeff t t (a :: word) = 0
                      @[simp]
                      theorem RoughPaths.WeakGeometricRoughPath.coeff_nil {T : Type u} {α : Type v} {R : Type w} [CommSemiring R] (X : WeakGeometricRoughPath T α R) (s t : T) :
                      X.coeff s t [] = 1
                      theorem RoughPaths.WeakGeometricRoughPath.shuffle {T : Type u} {α : Type v} {R : Type w} [CommSemiring R] (X : WeakGeometricRoughPath T α R) (s t : T) (u v : List α) :
                      X.coeff s t u * X.coeff s t v = Word.shuffleCoeff (X.increment s t) u v
                      theorem RoughPaths.WeakGeometricRoughPath.chen_eq {T : Type u} {α : Type v} {R : Type w} [CommSemiring R] (X : WeakGeometricRoughPath T α R) (s t u : T) :
                      @[reducible, inline]

                      Agreement of weakly geometric rough paths through word degree n — the generic graded agreement of Hopf rough paths for the word-length grading.

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                        theorem RoughPaths.WeakGeometricRoughPath.agreeUpToDegree_iff_coeff {T : Type u} {α : Type v} {R : Type w} [CommSemiring R] (X Y : WeakGeometricRoughPath T α R) (n : ) :
                        X.AgreeUpToDegree Y n ∀ (s t : T) (word : List α), word.length nX.coeff s t word = Y.coeff s t word
                        theorem RoughPaths.WeakGeometricRoughPath.eq_of_agreeUpToDegree_all {T : Type u} {α : Type v} {R : Type w} [CommSemiring R] {X Y : WeakGeometricRoughPath T α R} (h : ∀ (n : ), X.AgreeUpToDegree Y n) :
                        X = Y
                        theorem RoughPaths.WeakGeometricRoughPath.comapTime_comp {T : Type u} {α : Type v} {R : Type w} [CommSemiring R] {S : Type z} {U : Type y} (f : ST) (g : US) (X : WeakGeometricRoughPath T α R) :
                        @[simp]
                        theorem RoughPaths.WeakGeometricRoughPath.comapTime_unit {T : Type u} {α : Type v} {R : Type w} [CommSemiring R] {S : Type z} (f : ST) :
                        comapTime f (unit T α R) = unit S α R
                        theorem RoughPaths.WeakGeometricRoughPath.comapMapLetters_comp {T : Type u} {α : Type v} {R : Type w} [CommSemiring R] {β : Type z} {γ : Type y} (f : αβ) (g : βγ) (X : WeakGeometricRoughPath T γ R) :
                        @[simp]
                        theorem RoughPaths.WeakGeometricRoughPath.comapMapLetters_unit {T : Type u} {α : Type v} {R : Type w} [CommSemiring R] {β : Type z} (f : αβ) :
                        comapMapLetters f (unit T β R) = unit T α R
                        def RoughPaths.WeakGeometricRoughPath.logIncrementTruncated {T : Type u} {α : Type v} {R : Type w} [Field R] (X : WeakGeometricRoughPath T α R) (s t : T) (n : ) :
                        List αR

                        Truncated log-signature increment of a weakly geometric rough path.

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                          @[simp]
                          theorem RoughPaths.WeakGeometricRoughPath.logIncrementTruncated_comapMapLetters_coeff {T : Type u} {α : Type v} {R : Type w} [Field R] {β : Type z} (f : αβ) (X : WeakGeometricRoughPath T β R) (s t : T) (n : ) (word : List α) :
                          structure RoughPaths.ControlledWeakGeometricRoughPath (T : Type u) (α : Type v) (R : Type w) [Preorder T] [CommSemiring R] (size : RENNReal) (gauge : ENNRealENNReal) :
                          Type (max (max u v) w)

                          A controlled weakly geometric rough path with a word-coordinate bound.

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                            @[implicit_reducible]
                            instance RoughPaths.ControlledWeakGeometricRoughPath.instCoeControlled {T : Type u} {α : Type v} {R : Type w} [Preorder T] [CommSemiring R] {size : RENNReal} {gauge : ENNRealENNReal} :
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                            def RoughPaths.ControlledWeakGeometricRoughPath.ofControlled {T : Type u} {α : Type v} {R : Type w} [Preorder T] [CommSemiring R] {size : RENNReal} {gauge : ENNRealENNReal} (X : AlgebraicRoughPath.Controlled T α R size gauge) (hX : X.toAlgebraic.IsWeaklyGeometric) :

                            Regard an algebraically controlled rough path as controlled weakly geometric.

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                              theorem RoughPaths.ControlledWeakGeometricRoughPath.ext {T : Type u} {α : Type v} {R : Type w} [Preorder T] [CommSemiring R] {size : RENNReal} {gauge : ENNRealENNReal} {X Y : ControlledWeakGeometricRoughPath T α R size gauge} (h : X.toControlled = Y.toControlled) :
                              X = Y
                              theorem RoughPaths.ControlledWeakGeometricRoughPath.ext_iff {T : Type u} {α : Type v} {R : Type w} [Preorder T] [CommSemiring R] {size : RENNReal} {gauge : ENNRealENNReal} {X Y : ControlledWeakGeometricRoughPath T α R size gauge} :

                              Controlled weakly geometric rough paths are equivalent to controlled group-like algebraic ones.

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                                def RoughPaths.ControlledWeakGeometricRoughPath.toWeakGeometric {T : Type u} {α : Type v} {R : Type w} [Preorder T] [CommSemiring R] {size : RENNReal} {gauge : ENNRealENNReal} (X : ControlledWeakGeometricRoughPath T α R size gauge) :

                                Forget the analytic control and keep the weakly geometric rough path.

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                                  def RoughPaths.ControlledWeakGeometricRoughPath.toAlgebraic {T : Type u} {α : Type v} {R : Type w} [Preorder T] [CommSemiring R] {size : RENNReal} {gauge : ENNRealENNReal} (X : ControlledWeakGeometricRoughPath T α R size gauge) :

                                  Underlying algebraic rough path.

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                                    def RoughPaths.ControlledWeakGeometricRoughPath.control {T : Type u} {α : Type v} {R : Type w} [Preorder T] [CommSemiring R] {size : RENNReal} {gauge : ENNRealENNReal} (X : ControlledWeakGeometricRoughPath T α R size gauge) :

                                    The control attached to a controlled weakly geometric rough path.

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                                      theorem RoughPaths.ControlledWeakGeometricRoughPath.controlled {T : Type u} {α : Type v} {R : Type w} [Preorder T] [CommSemiring R] {size : RENNReal} {gauge : ENNRealENNReal} (X : ControlledWeakGeometricRoughPath T α R size gauge) :
                                      def RoughPaths.ControlledWeakGeometricRoughPath.coeff {T : Type u} {α : Type v} {R : Type w} [Preorder T] [CommSemiring R] {size : RENNReal} {gauge : ENNRealENNReal} (X : ControlledWeakGeometricRoughPath T α R size gauge) (s t : T) (word : List α) :
                                      R

                                      Signature coordinate of a controlled weakly geometric rough path.

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                                        def RoughPaths.ControlledWeakGeometricRoughPath.truncatedIncrement {T : Type u} {α : Type v} {R : Type w} [Preorder T] [CommSemiring R] {size : RENNReal} {gauge : ENNRealENNReal} (X : ControlledWeakGeometricRoughPath T α R size gauge) (n : ) (s t : T) :

                                        Truncated increment of a controlled weakly geometric rough path.

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                                          def RoughPaths.ControlledWeakGeometricRoughPath.comapMapLetters {T : Type u} {α : Type v} {R : Type w} [Preorder T] [CommSemiring R] {size : RENNReal} {gauge : ENNRealENNReal} {β : Type z} (f : αβ) (X : ControlledWeakGeometricRoughPath T β R size gauge) :

                                          Pull a controlled weakly geometric rough path back along a map of alphabets.

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                                          • One or more equations did not get rendered due to their size.
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                                            def RoughPaths.ControlledWeakGeometricRoughPath.comapTime {T : Type u} {α : Type v} {R : Type w} [Preorder T] [CommSemiring R] {size : RENNReal} {gauge : ENNRealENNReal} {S : Type z} [Preorder S] (f : ST) (hf : Monotone f) (X : ControlledWeakGeometricRoughPath T α R size gauge) :

                                            Pull a controlled weakly geometric rough path back along a monotone time map.

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                                            • One or more equations did not get rendered due to their size.
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                                              @[simp]
                                              theorem RoughPaths.ControlledWeakGeometricRoughPath.coeff_apply {T : Type u} {α : Type v} {R : Type w} [Preorder T] [CommSemiring R] {size : RENNReal} {gauge : ENNRealENNReal} (X : ControlledWeakGeometricRoughPath T α R size gauge) (s t : T) (word : List α) :
                                              X.coeff s t word = X.toAlgebraic.coeff s t word
                                              @[simp]
                                              theorem RoughPaths.ControlledWeakGeometricRoughPath.truncatedIncrement_apply {T : Type u} {α : Type v} {R : Type w} [Preorder T] [CommSemiring R] {size : RENNReal} {gauge : ENNRealENNReal} (X : ControlledWeakGeometricRoughPath T α R size gauge) (n : ) (s t : T) (word : { word : List α // word.length n }) :
                                              X.truncatedIncrement n s t word = X.coeff s t word
                                              theorem RoughPaths.ControlledWeakGeometricRoughPath.coordinate_bound {T : Type u} {α : Type v} {R : Type w} [Preorder T] [CommSemiring R] {size : RENNReal} {gauge : ENNRealENNReal} (X : ControlledWeakGeometricRoughPath T α R size gauge) {s t : T} (hst : s t) (word : List α) :
                                              size (X.coeff s t word) gauge word.length (X.control.toFun s t)
                                              @[simp]
                                              theorem RoughPaths.ControlledWeakGeometricRoughPath.coeff_comapMapLetters {T : Type u} {α : Type v} {R : Type w} [Preorder T] [CommSemiring R] {size : RENNReal} {gauge : ENNRealENNReal} {β : Type z} (f : αβ) (X : ControlledWeakGeometricRoughPath T β R size gauge) (s t : T) (word : List α) :
                                              (comapMapLetters f X).coeff s t word = X.coeff s t (List.map f word)
                                              @[simp]
                                              theorem RoughPaths.ControlledWeakGeometricRoughPath.toControlled_comapTime {T : Type u} {α : Type v} {R : Type w} [Preorder T] [CommSemiring R] {size : RENNReal} {gauge : ENNRealENNReal} {S : Type z} [Preorder S] (f : ST) (hf : Monotone f) (X : ControlledWeakGeometricRoughPath T α R size gauge) :
                                              @[simp]
                                              theorem RoughPaths.ControlledWeakGeometricRoughPath.coeff_comapTime {T : Type u} {α : Type v} {R : Type w} [Preorder T] [CommSemiring R] {size : RENNReal} {gauge : ENNRealENNReal} {S : Type z} [Preorder S] (f : ST) (hf : Monotone f) (X : ControlledWeakGeometricRoughPath T α R size gauge) (s t : S) (word : List α) :
                                              (comapTime f hf X).coeff s t word = X.coeff (f s) (f t) word
                                              @[simp]
                                              theorem RoughPaths.ControlledWeakGeometricRoughPath.control_comapMapLetters {T : Type u} {α : Type v} {R : Type w} [Preorder T] [CommSemiring R] {size : RENNReal} {gauge : ENNRealENNReal} {β : Type z} (f : αβ) (X : ControlledWeakGeometricRoughPath T β R size gauge) :
                                              @[simp]
                                              theorem RoughPaths.ControlledWeakGeometricRoughPath.control_comapTime {T : Type u} {α : Type v} {R : Type w} [Preorder T] [CommSemiring R] {size : RENNReal} {gauge : ENNRealENNReal} {S : Type z} [Preorder S] (f : ST) (hf : Monotone f) (X : ControlledWeakGeometricRoughPath T α R size gauge) :
                                              (comapTime f hf X).control = X.control.comap f hf
                                              @[simp]
                                              theorem RoughPaths.ControlledWeakGeometricRoughPath.comapMapLetters_id {T : Type u} {α : Type v} {R : Type w} [Preorder T] [CommSemiring R] {size : RENNReal} {gauge : ENNRealENNReal} (X : ControlledWeakGeometricRoughPath T α R size gauge) :
                                              theorem RoughPaths.ControlledWeakGeometricRoughPath.comapMapLetters_comp {T : Type u} {α : Type v} {R : Type w} [Preorder T] [CommSemiring R] {size : RENNReal} {gauge : ENNRealENNReal} {β : Type z} {γ : Type y} (f : αβ) (g : βγ) (X : ControlledWeakGeometricRoughPath T γ R size gauge) :
                                              @[simp]
                                              theorem RoughPaths.ControlledWeakGeometricRoughPath.comapTime_id {T : Type u} {α : Type v} {R : Type w} [Preorder T] [CommSemiring R] {size : RENNReal} {gauge : ENNRealENNReal} (X : ControlledWeakGeometricRoughPath T α R size gauge) :
                                              comapTime id X = X
                                              theorem RoughPaths.ControlledWeakGeometricRoughPath.comapTime_comp {T : Type u} {α : Type v} {R : Type w} [Preorder T] [CommSemiring R] {size : RENNReal} {gauge : ENNRealENNReal} {S : Type z} {U : Type y} [Preorder S] [Preorder U] (f : ST) (hf : Monotone f) (g : US) (hg : Monotone g) (X : ControlledWeakGeometricRoughPath T α R size gauge) :
                                              comapTime g hg (comapTime f hf X) = comapTime (f g) X
                                              def RoughPaths.ControlledWeakGeometricRoughPath.AgreeUpToDegree {T : Type u} {α : Type v} {R : Type w} [Preorder T] [CommSemiring R] {size : RENNReal} {gauge : ENNRealENNReal} (X Y : ControlledWeakGeometricRoughPath T α R size gauge) (n : ) :

                                              Agreement through degree n for the underlying weakly geometric rough paths.

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                                                theorem RoughPaths.ControlledWeakGeometricRoughPath.agreeUpToDegree_refl {T : Type u} {α : Type v} {R : Type w} [Preorder T] [CommSemiring R] {size : RENNReal} {gauge : ENNRealENNReal} (X : ControlledWeakGeometricRoughPath T α R size gauge) (n : ) :
                                                theorem RoughPaths.ControlledWeakGeometricRoughPath.agreeUpToDegree_iff_coeff {T : Type u} {α : Type v} {R : Type w} [Preorder T] [CommSemiring R] {size : RENNReal} {gauge : ENNRealENNReal} (X Y : ControlledWeakGeometricRoughPath T α R size gauge) (n : ) :
                                                X.AgreeUpToDegree Y n ∀ (s t : T) (word : List α), word.length nX.coeff s t word = Y.coeff s t word